java.lang.IllegalArgument Exception: No bean specified

hello all! i am trying to make a select drop down list,which is filled with values from database. i am having this error when i am trying to submit my form:java.lang.IllegalArgumentException: No bean specified. i have declared and instatiated in my form the variabe i use to store user's selection and i cant find what is still going wrong! the full description of the error is: